Solar load shifting a freezer

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SpookyAwol

626 posts

Ultimate Geek

#289179 17-Aug-2021 16:04

Does anyone have any advice about the effectiveness or ability to load shift a 280l chest freezer to sunlight hours?

Obviously you can add a timer to switch off x hours before morning and then turn it back on once solar generation starts.
Any thoughts on doing this and working out how long you could effectively turn the unit off for?

Any other ideas also greatly accepted :)

timmmay

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#2761608 17-Aug-2021 16:19

Would it use enough power to bother with?

SpookyAwol

626 posts

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#2761634 17-Aug-2021 16:34

Thats what I was wondering, its only 3 hours out of a day basically.

Jase2985

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#2761762 17-Aug-2021 18:56

buy a cheap power monitor plug and see how much it uses

nickb800

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#2761888 18-Aug-2021 05:48

By comparison, I've monitored the power use of our fridge and freezer. They are both around 240L and 5-10 year old Fisher and Paykels. Together, they average around 1.7kWh per day. I assume that is split roughly 50/50 - the freezer is colder, but the fridge is opened more often.

Based on 25 cents per kWh, that's around $80 in potential savings per year if you can put your freezer entirely on solar power.

I'd want to put a temperature probe in there and do some experiments before thinking about turning off the freezer overnight. One could envisage a solution with a Shelly and temperature probe - turn the power off during the day, but with an automatic override if say the temperature exceeds -10C.

Have to factor in that any failure in your control device could lead to food spoilage, which could wipe out several years potential savings

throbb

675 posts

Ultimate Geek

#2761917 18-Aug-2021 07:53

nickb800: By comparison, I've monitored the power use of our fridge and freezer. They are both around 240L and 5-10 year old Fisher and Paykels. Together, they average around 1.7kWh per day. I assume that is split roughly 50/50 - the freezer is colder, but the fridge is opened more often.

Based on 25 cents per kWh, that's around $80 in potential savings per year if you can put your freezer entirely on solar power.

I'd want to put a temperature probe in there and do some experiments before thinking about turning off the freezer overnight. One could envisage a solution with a Shelly and temperature probe - turn the power off during the day, but with an automatic override if say the temperature exceeds -10C.

Have to factor in that any failure in your control device could lead to food spoilage, which could wipe out several years potential savings

It would probably be closer to $20 for a chest freezer, they are many times more efficient than an upright, more so if they are both being opened frequently.

nickb800

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#2761976 18-Aug-2021 08:15

throbb:
nickb800: By comparison, I've monitored the power use of our fridge and freezer. They are both around 240L and 5-10 year old Fisher and Paykels. Together, they average around 1.7kWh per day. I assume that is split roughly 50/50 - the freezer is colder, but the fridge is opened more often.

Based on 25 cents per kWh, that's around $80 in potential savings per year if you can put your freezer entirely on solar power.

I'd want to put a temperature probe in there and do some experiments before thinking about turning off the freezer overnight. One could envisage a solution with a Shelly and temperature probe - turn the power off during the day, but with an automatic override if say the temperature exceeds -10C.

Have to factor in that any failure in your control device could lead to food spoilage, which could wipe out several years potential savings

It would probably be closer to $20 for a chest freezer, they are many times more efficient than an upright, more so if they are both being opened frequently.

I agree that chest freezers can be more efficient than verticals (though I'd note that they often have the same energy star rating) but I doubt they would be many times more efficient (for an equivalent number of 'door opens'). Worth bearing in mind that in vertical freezers with solid plastic fronts on the drawers (rather than wire mesh), any air disturbance from opening the door is largely contained to the area being accessed. This makes a big impact on efficiency.

jim.cox

224 posts

Master Geek

#2762153 18-Aug-2021 09:20

Jaycar sell a couple of solar controllers with a time-switched output feed.

The output is only 12v, so you would need an inverter.

As others have said, you would want to check the load.

You could also look at adding extra insulation - building a lined & insulated box around the freezer.

There are also some peltier device based units around which have significantly lower power needs

=mjc=
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SpookyAwol

626 posts

Ultimate Geek

#2763127 19-Aug-2021 15:57

jim.cox:

You could also look at adding extra insulation - building a lined & insulated box around the freezer.

I have a concern that putting a freezer inside a freezer may be counter productive and double my power bill